eater trait hostility has been associated with higher rates of smoking initiation, progression to heavier smoking, higher rates of smoking, persistence of smoking, and lower rates of success in smoking cessation treatment. Despite these findings, research on mechanisms linking smoking and hostility has been very limited. The overall aim of this project is to examine social, cognitive, and affective processes and their relation to smoking in low hostile (LH) and high hostile (HH) smokers in an effort to better understand the mechanisms through which hostility impacts smoking behavior. This research is guided by a sociocognitive model of hostility and smoking that suggests that HH smokers may show social information processing biases that make them vulnerable to interpersonal stress and may often smoke as a means of regulating their affect during and after social encounters. This model also suggests that nicotine withdrawal and its accompanying negative affect may further bias information processing in HH smokers making interpersonal interaction an even greater source of stress and a potentially powerful precipitant of smoking relapse. To begin to test this sociocognitive model, we propose in this R21 application to recruit 48 LH and 48 HH smokers for a laboratory study involving a baseline assessment and two experimental sessions, one in which participants are smoking ad lib and one in which they will have abstained from smoking for 12 hours. At the second and third sessions, participants will complete a modified visual probe detection task, a facial emotion change detection task, and an interpersonal stressor. Participants will be assigned to smoke immediately after the stressor in one session and 15 minutes after the stressor in the other. Analyses will be conducted to test the hypothesis that nicotine deprivation will further bias processing of threatening/hostile social information and enhance responding to interpersonal stress in HH smokers relative to LH smokers. We also will test the hypothesis that immediate smoking after an interpersonal stressor, compared to delayed smoking, will be associated with a relatively more steep reduction in negative affect and cigarette craving in HH smokers compared to LH smokers. Results of this study will begin to elucidate interpersonal, affective, and cognitive mechanisms that may maintain smoking in HH individuals and should provide direction as to the types of treatment approaches that might be most effective with these high-risk smokers. [unreadable] [unreadable]